There was a lot of Japanese product in the 70s/80s that was only sold in Japan as a premier or flagship series that was very good, and often very expensive. Much of what was sold internationally was not as good, and a great deal of it looked the same or similar to the flagship stuff so you need to research whether it was actually the Japanese or international. Most of the sites dedicated to the premier lines are in Japanese which makes this difficult. Even though I thought I'd researched well a couple of years back, I got burned on a similar product. Fortunately I onsold them on gumtree for little loss to someone who just thought they looked 'rockin'. I thought they sounded like junk.
I don't know the ones pictured, but unless they are very cheap and you're willing to take a risk, most likely they are pretty average, but go have a listen, they might be pearls.
I don't know the ones pictured, but unless they are very cheap and you're willing to take a risk, most likely they are pretty average, but go have a listen, they might be pearls.